Office chair

ABSTRACT

A chair includes a chair leg, a backrest, a seat and a support member. The chair leg includes a stem that has a connecting end at a top thereof. The seat is integrally formed and has a seat frame, two reinforcement beams and a support member disposed between the reinforcement beams. The support member includes a plurality of ribs, and an axle connecting portion and an adjusting portion surrounded by the ribs. The axle connecting portion has an axle hole to couple with the connecting end. The support member has a support portion below the axle connecting portion. The adjusting portion includes a fixation hole. A bottom of the support member includes an axle mounting flange. One end of a support beam connects with the backrest and the other end of the support beam pivotally connects with the axle mounting flange.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a chair, and more particularly to an office chair whose seat has a support member disposed under the seat. The support member can sustain the user's body weight and does not need other parts to reinforce the structure of chair. Thus, the manufacture cost is reduced.

2. The Prior Arts

Referring to FIG. 1, a conventional office chair comprises a seat 10, a backrest 20 and a chair leg 30. The seat 10 includes a seat frame 12 on which is placed a seat cushion 11. Two reinforcement beams 13 are mounted under the seat frame 12 for supporting the weight of the seat frame 12 and reinforcing the seat frame 12. The reinforcement beam 13 is provided with a plurality of assembly holes, whereas the seat cushion 11 may be a foam pad or a mesh stretched across the seat frame 12. The backrest 20 includes a back frame 22 on which is disposed a backrest cushion 21. The backrest cushion 21 may be a foam pad or a mesh stretched across the backrest frame 22. Reinforcement ribs 23 are provided on a rear side of the back frame 22 to reinforce the structure of the back frame 22. A plurality of assembly holes are formed on the reinforcement ribs 23. The chair leg 30 is a column as a supporting structure. A bottom end of the chair leg 30 extends outward to form multiple radial pedestal feet coupled with casters 35. A plurality of screws passes through the assembly holes of the reinforcement beams 13 to securely fix the reinforcement beams 13 with a base 31. A top end of the chair leg 30 is coupled with the base 31. The reinforcement ribs 23 of the backrest 20 are fastened with a support beam 32 through screws engaging with the assembly holes provided on the reinforcement ribs 23, and are also coupled downward with the base 31 (not shown). The base 31 is mainly made of metal to provide sufficient strength to sustain the pressure exerted thereon by the reinforcement beams 13. The seat frame 12 and the back frame 22 are usually made by plastics injection molding, which can reduce manufacturing cost and maintain necessary structure strength.

FIG. 2 is an exploded view showing a seat of a conventional office chair designed by the applicant. A seat cushion 11 includes a mesh 111 that is stretched to encapsulate an inner frame 112. A clamp 113 is then mounted in a slot (not shown) at an outer peripheral edge of the inner frame 112 to securely fix the mesh 111 on the seat cushion 11. Thus, the mesh 111 fixed on the seat cushion 11 has the strength to support a user's body weight. As shown in FIG. 2, reinforcement beams 13 can only reinforce the seat frame 12 to sustain body weight. However, the reinforcement beams 13 still need to assemble with the base 31, which connects with the chair leg 30, to sustain the pressure and torques produced by the body weight. Further, the top end of the chair leg 30 may also be provided with a pressure adjustment unit for seat height adjustment. Thus, the base 31 is usually made of metal and is formed thick enough to provide sufficient strength, which increases the weight of the chair and the manufacture cost. Therefore, it is an important issue to design a chair that can reduce the manufacture cost and still have sufficient structural strength.

SUMMARY OF THE INVENTION

A primary objective of the present is to provide an office chair whose strength is strong enough to sustain the user's body and manufacture cost is lower than conventional office chairs.

In order to achieve the objective, a seat of an office chair according to the present invention includes a support member. The support member is integrally formed with the seat by injection molding and can be directly mounted on a top of a chair leg. The seat may incorporate a pressure adjustment unit for seat height adjustment, and can be easily coupled with a backrest. Therefore, the seat height is adjustable and the manufacture cost is lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be apparent to those skilled in the art by reading the following detailed description of a preferred embodiment thereof, with reference to the attached drawings, in which:

FIG. 1 is a perspective view showing a conventional office chair;

FIG. 2 is an exploded view showing a seat of another conventional office chair;

FIG. 3 is an exploded view showing a seat and a chair leg of an office chair according to an embodiment of the present invention;

FIG. 4 is a side cross-sectional view showing the seat, the chair leg and a support beam that connects the seat with a backrest; and

FIG. 5 is a front cross-sectional view showing the seat and the chair leg according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 3, an office chair according to an embodiment of the present invention comprises a chair leg 30, a seat mounted on the chair leg 30 and a backrest (not shown in figures). The seat includes a seat cushion 11′, a seat frame 12′, two reinforcement beams 13′ disposed in the seat frame 12′ and a support member 14 disposed between the reinforcement beams 13′. The support member 14 is in a plate shape that extends upwards at edges to define an open space in which a plurality of ribs 144 is arranged across one another for reinforcing the support member 14. Thus, it reduces the amount of plastic material used during plastic injection molding, and also facilitates mold release. A primary feature of the present invention is that a central region of the support member 14 has an axle connecting portion 141 surrounded by the ribs 144. A bottom of the axle connecting portion 141 has an axle hole 1411. A side of the axle connecting portion 141 has a pivot portion 143 provided with a pair of pivot connecting sleeves 1431. An end of the support member 14 proximate to the backrest has an adjusting portion 142 provided with a fixation hole 1421.

Referring to FIGS. 3 to 5, the ribs 144 formed in the support member 14 provide necessary strength to the support member 14. The axle connecting portion 141, the adjusting portion 142 and the pivot portion 143 are surrounded by the crisscrossed ribs 144. A bottom of the support member 14 includes a support portion 1412 below the axle connecting portion 141. The axle hole 1411 penetrates through the axle connecting portion 141 and the support portion 1412. The support portion 1412 is thicker than the support member 14 and is larger in area than the axle connecting portion 141. Thus, the whole axle connecting portion 141 are located in a corresponding area above the support portion 1412. Because both sides of the axle connecting portion 141 respectively has the support portion 1412 and the ribs 144 surrounding the axle connecting portion 141 to reinforce the structure, it can prevent the axle connecting portion 141 from deformation or fracture due to user's body weight. The pivot portion 143 includes an edge opening to the outside of the support member 14 and an inner opening to the axle connecting portion 141. The two pivot connecting sleeves 1431 disposed in the pivot portion 143 are located at both sides of the edge opening, respective. The edge opening and the inner opening are aligned with a central axis of the axle hole 1411. Flanges 1422 are also formed at the outer periphery of the fixation hole 1421 of the adjusting portion 142 for reinforcing its structural strength. A metal screw nut may also be provided in the fixation hole 1421. In addition, a portion of the support member 14 corresponding to the location of the adjusting portion 142 may also extend outside of the reinforcement beam 13′. Referring to FIG. 4, an axle mounting flange 146 protrude downward between the support portion 1412 and the fixation hole 1421 on the bottom of the support member 14.

During assembly, a connecting end 302 located on a top of a stem 301 of the chair leg 30 has a threaded portion that connects with the axle hole 1411 and screws with a screw nut 33. Thus, the connecting end 302 is fixedly secured under the axle connecting portion 141. The support member 14 is then assembled on the chair leg 30 to support downward pressing load transmitted from the seat frame 12′ and the thick support portion 1412 also help to sustain the load. An adjustment lever 34 assembled with the support member 14 passes through the edge opening and the inner opening of the pivot portion 143. The adjustment lever 34 is configured to interact with a pressure adjustment unit for seat height adjustment. The pressure adjustment unit may be a hydraulic adjustment unit or a pneumatic adjustment unit. The pressure adjustment unit comprising the stem 301 adapted to be pressed downward and a contact end 303 provided at a top thereof. An intermediate portion of the adjustment lever 34 includes two rotary axle portions 343 perpendicularly protruding outward at two sides of the adjustment lever 34. A first end of the adjustment lever 34 includes a pressing portion 341 adapted to press the contact end 303. A second end of the adjustment lever 34 has an operating handle 342 adapted to receive the user's operation. The adjustment lever 34 passes through the edge opening and the inner opening of the pivot portion 143 and the rotary axle portions 343 respectively pivotally connect with the pivot connecting sleeves 1431. Once the adjustment lever 34 is assembled, the pressing portion 341 is positioned above the contact end 303, whereas the operating handle 342 is accessible by the user for manual operation. When the operating handle 342 is pulled upward, the adjustment lever 34 rotates owing to the pivot connection between the rotary axle portions 343 and the pivot connecting sleeves 1431, causing the pressing portion 341 to press downward against the contact end 303 and the stem 301 to perform seat height adjustment. Further, the office chair has a support beam 32 to connect the backrest and the seat. After the support beam 32 is pivotally connected with the axle mounting flange 146, a fixing screw 321 is inserted through a threaded hole of the support beam 32, and the screw nut in the fixation hole 1421 of the support member 14. Through the fixture of the fixing screw 321 and the support points provided by the axle mounting flange 146, the support beam 32 is able to support the backrest 20 mounted on an upper end thereof. Moreover, the fixing screw may also adjust the backrest.

FIG. 5 is another cross-sectional view showing the seat and the chair leg 30 according to the present invention. One of advantages of the support member 14 is that the manufacture cost is reduced, whereas the axle connecting portion 141, the pivot portion 143 and the adjusting portion 142 provide sufficient strength to the seat for maintaining the functionality of each elements while facilitating the manufacture and assembly of the chair structure.

Although the present invention has been described with reference to the preferred embodiment thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims. 

1. An office chair, comprising: a chair leg including a stem that has a connecting end at a top thereof; a seat including a seat frame that has at least two reinforcement beams; a backrest connected with a support beam; a support member disposed between the reinforcement beams and integrally formed with the reinforcement beams and the seat frame; wherein a plurality of ribs are formed on the support member, the support member comprises an axle connecting portion and an adjusting portion, the axle connecting portion and the adjusting portion are respectively surrounded by the ribs, the axle connecting portion has an axle hole adapted to couple with the connecting end of the chair leg, the adjusting portion includes an fixation hole, an axle mounting flange is provided on a bottom of the support member corresponding to the adjusting portion, an end of the support beam is pivotally connected with the axle mounting flange and the other end of the support beam is coupled with the backrest, and a threaded hole of the support beam is corresponding to the fixation hole.
 2. The chair according to claim 1, wherein the chair leg includes a pressure adjustment unit for seat height adjustment, the pressure adjustment unit comprises the stem and a contact end provided at the top of the stem to adjust the seat height.
 3. The chair according to claim 1, wherein a top of the support beam is provided with a plurality of assembly holes through which screws are engaged for securely connecting the support beam with the backrest.
 4. The chair according to claim 1, wherein a fixing screw is inserted through the fixation hole of the adjusting portion and the threaded hole of the support beam to connect the support member with the support beam.
 5. The chair according to claim 1, wherein the support member comprises a pivot portion proximate to the axle connecting portion, the pivot portion includes an edge opening to an outside of the support member, two pivot connecting sleeves are disposed in the pivot portion and are respective located at both sides of the edge opening.
 6. The chair according to claim 5, wherein an end of an adjustment lever passes through the edge opening and the adjustment lever comprises two rotary axle portions respectively pivotally connected with the pivot connecting sleeves.
 7. The chair according to claim 1, wherein the ribs on the support member cross one another, and surround the axle connecting portion and the adjusting portion.
 8. The chair according to claim 1, wherein the bottom of the support member comprises a support portion under the axle connecting portion, the support portion has an area larger than that of the axle connecting portion, the axle hole penetrates through the axle connecting portion and the support portion, and the support portion is thicker than the support member. 